Integrated circuits have evolved into complex devices that include millions of transistors, capacitors and resistors on a single chip. The evolution of chip design results in faster circuitry and greater circuit density. As the demand for integrated circuits continues to rise, chip manufactures have demanded semiconductor process tooling having increased wafer throughput, greater product yield, and more robust processing equipment. To meet demands, tooling is being developed to minimize particle contamination and increase the service life of tool components.
One source of particle generation is the lift pins utilized to space a substrate from a substrate support, typically in a processing chamber. The lift pins generally reside in guide holes disposed through the substrate support. The upper ends of the lift pins are typically flared to prevent the pins from passing through the guide holes. The lower ends of the lift pins extend below the substrate support and are actuated by a lift plate that contacts the pins at their lower ends. The lift plate is movable in a vertical direction between upper and lower positions. In the upper position, the lift plate moves the lift pins through the guide holes formed through the substrate support to extend the flared ends of the lift pins above the substrate support, thereby lifting the substrate into a spaced apart relation relative to the substrate support to facilitate substrate transfer.
One problem that has been observed in the prior art is particle generation attributed to contact between the lift pins and the guide holes as the lift pins move through the substrate support. Specifically, contact of the sides of the lift pin with the bottom edge of the guide hole may cause deep scratches over the entire length of the lift pin. Additionally, as the scratched pin repeatedly passes through the guide holes of the substrate support, the lift pin becomes more susceptible to binding and galling, resulting in shortened lift pin service life.
Therefore, there is a need in the art for an improved lift pin.